Philanthropy and business pair perfectly at Pencils of Promise (PoP), a New York City-based nonprofit that funds and builds classrooms and schools in South America, Africa and Asia.

"There's a new ecosystem of emerging Millennial organizations that sees businesses as partners," says founder and CEO Adam Braun. "Really great partners."

Case in point: During back-to-school season last year, PoP collaborated with cosmetics-sample company Birchbox on a special-edition "Beauty School Supply Kit" that sported a ruler-themed design. In August Birchbox donated 15 percent of total sales from its online shop to PoP--enough money to build an entire school. (On average, PoP can build a classroom for $10,000 and a school for $25,000.)

It's those strategic partnerships--including collaborations with major players such as Google, Viacom and Starbucks--that have really helped the PoP community thrive. Braun says most of the successful ventures grew out of his existing network of colleagues and family. In fact, Braun's brother Scooter is the manager of one of PoP's prominent supporters, Justin Bieber, who has served as an ambassador for the organization since 2010.

Birchbox co-founder Hayley Barna, meanwhile, was a colleague at Braun's first job. "She was the first person I reported directly to," he recalls. "The idea was that when our organiza-tions took off, we should find a way
to work together."

PoP has partnered with eyewear company Warby Parker, which co-branded two sunglass frames with PoP last year; the organization received $30 for every pair sold, enough to build a classroom in Guatemala and provide a year of education for 200 children. Free music-streaming service Songza put together a PoP-inspired playlist for studying that raised money with each listen, resulting in another new school. Poppin, a maker of hip office supplies, is raising money to build four schools with PoP this year.

The nonprofit stemmed from an encounter Braun had during a college study-abroad program in India. One day he asked a boy who was begging on the streets what he wanted most in the world. The answer: a pencil. The boy's response stuck with him.

While working as a consultant with Bain & Company, Braun used his vacation time to take backpacking trips in developing countries, handing out pens and pencils. He founded PoP in 2008; two years later, he left Bain to work on the nonprofit full time. The organization, which has helped build more than 103 schools, classrooms and dorms, now has offices in Ghana, Guatemala, Nicaragua and Laos, and about 75 global staff members.

"We find a way to create value for growing startups, because the key to a successful partnership is not to be a traditional nonprofit, but to [give] purpose to their brand," Braun says. "Startups are finding that new users and customers expect companies to make the world better in some capacity, and so the most effective way is to partner with a great nonprofit organization."